Turbine vane cooling arrangement

ABSTRACT

A vane includes a pair of airfoils having a plurality of film cooling holes that extend through an exterior surface of the airfoils, the plurality of film cooling holes including at least a first subset of film cooling holes, wherein the first subset of film cooling holes break through the exterior surface at geometric coordinates set forth herein. Each of the geometric coordinates is measured from a reference point on a leading edge rail of a platform of the vane.

BACKGROUND

This disclosure relates to a gas turbine engine, and more particularly to a turbine vane that may be incorporated into a gas turbine engine. The vane's airfoils and platforms include a plurality of film cooling holes as part of a cooling arrangement.

Gas turbine engines typically include a compressor section, a combustor section and a turbine section. During operation, air is pressurized in the compressor section and is mixed with fuel and burned in the combustor section to generate hot combustion gases. The hot combustion gases are communicated through the turbine section, which extracts energy from the hot combustion gases to power the compressor section and other gas turbine engine loads.

Both the compressor and turbine sections may include alternating series of rotating blades and stationary vanes that extend into the core flow path of the gas turbine engine. For example, in the turbine section, turbine blades rotate and extract energy from the hot combustion gases that are communicated along the core flow path of the gas turbine engine. The turbine vanes, which generally do not rotate, guide the airflow and prepare it for the next set of blades.

Each of the blades and vanes include airfoils that extend into the core flow path of the gas turbine engine between inner and outer platforms. Cooling airflow is communicated into an internal core of the airfoil and can be discharged through the plurality of film cooling holes to provide a boundary layer of film cooling air along the external surface of the airfoil and platforms. The film cooling air provides a barrier that protects the underlying substrate of the vane from the hot combustion gases that are communicated within the core flow path.

SUMMARY

In one exemplary embodiment a vane includes a pair of airfoils having a plurality of film cooling holes that extend through an exterior surface of the airfoils, the plurality of film cooling holes including at least a first subset of film cooling holes, wherein the first subset of film cooling holes break through the exterior surface at geometric coordinates in accordance with Cartesian coordinate values of X, Y and Z as set forth in Table 1, wherein each of the geometric coordinates is measured from a reference point on a leading edge rail of a platform of the vane.

In another example of the above described vane the Cartesian coordinate values of Table 1 are expressed in inches.

In another example of any of the above described vanes the reference point includes a pin hole of the platform.

In another example of any of the above described vanes the plurality of film cooling holes are spaced along a span of the airfoil body in multiple collinearly aligned rows.

In another example of any of the above described vanes the first subset of film cooling holes are disposed on a pressure side filet of the airfoil body.

Another example of any of the above described vanes further includes at least a second subset of film cooling holes disposed on a pressure side, a suction side and a leading edge of the airfoil body.

In another example of any of the above described vanes the airfoils extend between inner and outer platforms, the inner and outer platforms include a second plurality of film cooling holes that extend through an exterior surface of the platforms.

In another example of any of the above described vanes the plurality of film cooling holes included in the first subset of film cooling holes are the only cooling holes disposed within a radially outward fileted region of a pressure side of each airfoil.

In another example of any of the above described vanes the vane is a first turbine stage vane.

An exemplary method for cooling a vane doublet includes generating a film cooling layer across a pressure side filet of each airfoil in the vane doublet by passing air through a plurality of film cooling holes that extend through an exterior surface of the airfoils, the plurality of film cooling holes including at least a first subset of film cooling holes, wherein the first subset of film cooling holes break through the exterior surface at geometric coordinates in accordance with Cartesian coordinate values of X, Y and Z as set forth in Table 1, wherein each of the geometric coordinates is measured from a reference point on a leading edge rail of a platform of the vane.

Another example of the above described method for cooling a vane doublet further includes generating a film cooling layer across at least one of a pressure side, a suction side and a leading edge of the airfoil body by passing air through a plurality of film cooling holes disposed across the at least one of the pressure side, the suction side and the leading edge.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be further understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 illustrates a schematic, cross-sectional view of a gas turbine engine.

FIG. 2 schematically illustrates a doublet stator vane that can be incorporated into a gas turbine engine.

FIG. 3 schematically illustrates another view of the vane of FIG. 2.

FIG. 4 schematically illustrates a cross-sectional view of one of an airfoil that includes a plurality of film cooling holes as part of an airfoil cooling arrangement of the vane.

The embodiments, examples and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates a gas turbine engine 20. The exemplary gas turbine engine 20 is a two-spool turbofan engine that generally incorporates a fan section 22, a compressor section 24, a combustor section 26 and a turbine section 28. Alternative engines might include an augmenter section (not shown) among other systems for features. The fan section 22 drives air along a bypass flow path B, while the compressor section 24 drives air along a core flow path C for compression and communication into the combustor section 26. The hot combustion gases generated in the combustor section 26 are expanded through the turbine section 28. Although depicted as a turbofan gas turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to turbofan engines and these teachings could extend to other types of engines, including but not limited to, three-spool engine architectures.

The gas turbine engine 20 generally includes a low speed spool 30 and a high speed spool 32 mounted for rotation about an engine centerline longitudinal axis A. The low speed spool 30 and the high speed spool 32 may be mounted relative to an engine static structure 33 via several bearing systems 31. It should be understood that additional bearing systems 31 may alternatively or additionally be provided.

The low speed spool 30 generally includes an inner shaft 34 that interconnects a fan 36, a low pressure compressor 38 and a low pressure turbine 39. The high speed spool 32 includes an outer shaft 35 that interconnects a high pressure compressor 37 and a high pressure turbine 40. In this embodiment, the inner shaft 34 and the outer shaft 35 are supported at various axial locations by bearing systems 31 positioned within the engine static structure 33.

A combustor 42 is arranged between the high pressure compressor 37 and the high pressure turbine 40. A mid-turbine frame 44 may be arranged generally between the high pressure turbine 40 and the low pressure turbine 39. The mid-turbine frame 44 supports one or more bearing systems 31 of the turbine section 28. The mid-turbine frame 44 may include one or more airfoils 46 that may be positioned within the core flow path C.

The inner shaft 34 and the outer shaft 35 are concentric and rotate via the bearing systems 31 about the engine centerline longitudinal axis A, which is co-linear with their longitudinal axes. The core airflow is compressed by the low pressure compressor 38 and the high pressure compressor 37, is mixed with fuel and burned in the combustor 42, and is then expanded over the high pressure turbine 40 and the low pressure turbine 39. The high pressure turbine 40 and the low pressure turbine 39 rotationally drive the respective high speed spool 32 and the low speed spool 30 in response to the expansion.

In some non-limiting examples, the gas turbine engine 20 is a high-bypass geared aircraft engine. In a further example, the gas turbine engine 20 bypass ratio is greater than about six (6:1). The example gas turbine engine 20 can be a geared turbofan engine that includes an epicyclic gear train, such as a planetary gear system or other gear system. The example epicyclic gear train has a gear reduction ratio of greater than about 2.3, and in another example is greater than about 2.5:1. The geared turbofan enables operation of the low speed spool 30 at higher speeds which can increase the operational efficiency of the low pressure compressor 38 and low pressure turbine 39 and render increased pressure in a fewer number of stages.

The low pressure turbine 39 pressure ratio is pressure measured prior to the inlet of the low pressure turbine 39 as related to the pressure at the outlet of the low pressure turbine 39 prior to an exhaust nozzle of the gas turbine engine 20. In one non-limiting embodiment, the bypass ratio of the gas turbine engine 20 is greater than about ten (10:1), the fan diameter is significantly larger than that of the low pressure compressor 38, and the low pressure turbine 39 has a pressure ratio that is greater than about 5 (5:1). It should be understood, however, that the above parameters are only exemplary of one embodiment of a geared architecture engine and that the present disclosure is applicable to other gas turbine engines including direct drive turbofans.

A significant amount of thrust is provided by the bypass flow B due to the high bypass ratio. The fan section 22 of the engine 20 is designed for a particular flight condition—typically cruise at about 0.8 Mach and about 35,000 feet (10,668 meters). The flight condition of 0.8 Mach and 35,000 ft (10,668 meters), with the engine at its best fuel consumption—also known as “bucket cruise Thrust Specific Fuel Consumption (‘TSFC’)”—is the industry standard parameter of lbm of fuel being burned divided by lbf of thrust the engine produces at that minimum point. “Low fan pressure ratio” is the pressure ratio across the fan blade alone, without a Fan Exit Guide Vane (“FEGV”) system. The low fan pressure ratio as disclosed herein according to one non-limiting embodiment is less than about 1.55. In another non-limiting embodiment the low fan pressure ratio is less than about 1.45. In another non-limiting embodiment the low fan pressure ratio is from 1.1 to 1.45. “Low corrected fan tip speed” is the actual fan tip speed in ft/sec divided by an industry standard temperature correction of [(Tram °R)/(518.7°R)]^(0.5). The “Low corrected fan tip speed” as disclosed herein according to one non-limiting embodiment is less than about 1150 ft/second (350.5 meters/second).

Each of the compressor section 24 and the turbine section 28 may include alternating rows of rotor assemblies and vane assemblies (shown schematically) that carry one or more airfoils that may extend into the core flow path C. For example, the rotor assemblies can carry a plurality of rotating blades 25, while each vane assembly can carry a plurality of vanes 27 that extend into the core flow path C. The blades 25 of the rotor assemblies create or extract energy (in the form of pressure) from core airflow that is communicated through the gas turbine engine 20. The vanes 27 of the vane assemblies direct core airflow to the blades 25 of the rotor assemblies to either add or extract energy.

Various components of the gas turbine engine 20, including airfoils of the compressor section 24 and the turbine section 28, may be subjected to repetitive thermal cycling under widely ranging temperatures and pressures. The hardware of the turbine section 28 is particularly subjected to relatively extreme operating conditions. Therefore, some components may require airfoil cooling arrangements for cooling the airfoils that extend into the core flow path C. Exemplary airfoil cooling arrangements that include internal cooling circuits and film cooling holes are described herein.

FIGS. 2 and 3 illustrate a doublet stator vane 50 that may be incorporated into a gas turbine engine, such as the gas turbine engine 20. A “doublet” includes a pair of airfoils joined to the same inner and outer platforms. The vane 50 of this particular embodiment is a first stage turbine vane of the turbine section 28. However, this disclosure is not limited to this particular vane and could extend to any vane that is disposed within the core flow path C of the gas turbine engine 20.

The vane 50 includes two airfoils 52 that extend between an inner platform 54 (on an inner diameter side) and an outer platform 56 (on an outer diameter side). Each airfoil 52 includes a leading edge 58, a trailing edge 60, a pressure side 62 and a suction side 64. Each airfoil 52, including the pressure side 62 and the suction side 64, extends in chord Cx between the leading edge 58 and the trailing edge 60 and extends in span S between the inner platform 54 and the outer platform 56.

A gas path 70 is communicated axially downstream through the gas turbine engine 20 in a direction that extends from the leading edge 58 toward the trailing edge 60 of the airfoil 52. The gas path 70 (for the communication of core airfoil along the core flow path C) extends between an inner gas path 72 associated with the inner platform 54 and an outer gas path 74 associated with the outer platform 56 of the vane 50. The inner platform 54 and the outer platform 56 are connected to the airfoils 52 at the inner and outer gas paths 72, 74 via fillets 75.

Both the inner platform 54 and the outer platform 56 include leading edge rails 66 and trailing edge rails 68 having one or more engagement features 69 for mounting the vane 50 to the gas turbine engine 20, such as to an engine casing. Other engagement feature configurations are contemplated as within the scope of this disclosure, including but not limited to, hooks, rails, bolts, rivets, tabs and/or other features that can be incorporated into the vane 50 to retain the vane 50 to the gas turbine engine 20. In this exemplary embodiment, the leading edge rail 66 of the inner platform 54 includes a pin hole 82 having a center point 84 (See FIG. 2).

Referring to FIG. 4, the airfoils 52 include an airfoil cooling arrangement that can include an internal cooling circuit 76 and a plurality of film cooling holes 78 that extend through an exterior surface 53 of the airfoil 52. In the illustrated example, the filets 75 on the pressure side of each vane 50 are exposed to heat related stresses and a subset of the film cooling holes 78 are positioned on the pressure side filets 75. The internal cooling circuit 76 can receive a cooling airflow CA to cool the internal surfaces of the airfoil 50 (See FIG. 3). In one exemplary embodiment, the cooling airflow CA is a bleed airflow that can be sourced from the compressor section 24 or any other portion of the gas turbine engine 20 that is upstream from the vane 50. The internal cooling circuit 76 may include one or more cavities 80 that define hollow openings within each airfoil 52. The cooling airflow CA can be communicated through the cavities 80, which extend across an entire length of the airfoil 52, to cool the internal surfaces of the airfoil 52.

The plurality of film cooling holes 78 of the airfoil cooling arrangement can be formed through the airfoil 52 (between the exterior surface 53 and one or more of the cavities 80) such that each film cooling hole 78 breaks out through the exterior surface 53 of the airfoil 52. In this exemplary embodiment, the filets 75 on the pressure side 62 of each vane include film cooling holes 78. In addition, film cooling holes can be included at other locations of the leading edge 58, the pressure side 62 and the suction side 64. The film cooling holes 78 may embody a cone shape or a round shape. Other shapes are also contemplated as within the scope of this disclosure.

FIG. 4 illustrates a cross-sectional view of an exemplary airfoil 50. The internal cooling circuit 76 of the airfoil 50 includes multiple cavities 80A-80C that can receive cooling airflow CA to cool the internal surfaces of the airfoil 50. In alternative configurations, alternative internal cooling cavity configurations can be utilized and achieve similar results. The plurality of film cooling holes 78 are in fluid communication with one or more of the cavities 80A-80C. Cooling airflow CA can be communicated into and through the cavities 80A-80C and can then be discharged through the plurality of film cooling holes 78 to provide a boundary layer of film cooling air along the exterior surface 53 of the airfoil 50. The film cooling air may provide a barrier that protects the underlying substrate of the airfoil 50 from the hot combustion gases that are communicated within the core flow path C.

The plurality of film cooling holes 78 are spaced apart along the span S of the airfoil 52 for discharging the cooling airflow CA and providing a boundary layer of film cooling air along the exterior surface 53 of the airfoil 52. In this exemplary embodiment, with reference to FIG. 4 and Table 1, the pressure side 62 includes PWA, PWB, PWC, PWD, etc. of film cooling holes 78 of film cooling holes 78. Additional holes can be provided but are not shown for clarity. In this disclosure, holes identified with the letter “P” refer to the rows of the pressure side 62. The locations shown in FIG. 4 are schematic.

The breakout point of each film cooling holes 78 refers to the geometric location along the vane 50 at which the film cooling hole centerline breaks through or protrudes out of the exterior surface of the vane 50. The breakout points of each of the plurality of film cooling holes 78 can be described in terms of sets of Cartesian coordinates, provided in Table 1 (airfoils), defined along x, y and z axes as measured from a specific reference point of the vane 50, as is further discussed below. As shown in FIGS. 2 and 3 (with continued reference to FIG. 1), the x axis is defined along the direction of the engine centerline longitudinal axis A, the y axis is defined in a substantially circumferential or rotational direction about the engine centerline longitudinal axis A, and the z axis is defined in a radial direction that is substantially perpendicular to the engine centerline longitudinal axis A.

In the exemplary embodiment, each of the geometric coordinates are measured from a pin hole 82 of the leading edge rail 66 of the inner platform 54 of the vane 50. By measuring the geometric coordinates (in terms of x, y and z values) from a center point 84 of the pin hole 82, the external break through points of a subset of the film cooling holes 78 of the airfoil 52. In the exemplary embodiment, the subset of film cooling holes 78 are the only film cooling holes breaking out in the radially outward filet 75 of the pressure side of each airfoil. Additional film cooling holes 78 are disposed across the surface of the airfoil. The Table 1 values for the x, y and z coordinates represent the true position of a nominal part and are listed in inches in this embodiment. However, the values of the Tables could be converted to millimeters by multiplying by 25.4, or could be converted to any other units. In other words, due to manufacturing tolerances, the external breakout of the centerline of each film cooling hole 78 can fall within a 0.200 inch diameter circle enscribed on the surface of the airfoil 50.

Table 1 identify each film cooling hole 78 by assigning a unique, three-letter identifier to each film cooling hole 78. The first two letters of the three-letter identifier identify the row (PW) where the film cooling hole is located. The third letter corresponds to the specific hole number of a particular row identified by the first two letters. The film cooling holes of each group are numbered from back to front, right airfoil to left airfoil, with the letter A representing the film cooling hole 78 closest to the trailing edge 60 on the right airfoil 52, B representing the film cooling hole 78 closest to the leading edge 58 on the right airfoil 52, and subsequent letters assigned to the film cooling holes 78 in the same manner on the left airfoil (i.e., C, D).

TABLE 1 airfoil cooling holes Hole Name X Y Z PWA 0.617-1.017 1.542-1.942 2.200-2.600 PWB 0.445-0.845 1.329-1.729 2.292-2.692 PWC 0.617-1.017 −0.290-0.110   2.263-2.663 PWD 0.445-0.845 −0.517-−0.117 2.313-2.713

The hole locations defined in Table 1 are defined at ambient, non-operating, conditions on a coated doublet stator vane 50.

Although the different non-limiting embodiments are illustrated as having specific components, the embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments.

In further examples, additional film cooling holes 78 can be included disposed across gaspath surfaces of the inner and outer platforms 54, 56 to provide similar film cooling benefits to the platform bodies.

It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be understood that although a particular component arrangement is disclosed and illustrated in these exemplary embodiments, other arrangements could also benefit from the teachings of this disclosure.

The foregoing description shall be interpreted as illustrative and not in any limiting sense. A worker of ordinary skill in the art would recognize that various modifications could come within the scope of this disclosure. For these reasons, the following claims should be studied to determine the true scope and content of this disclosure. 

What is claimed is:
 1. A vane comprising: a pair of airfoils having a plurality of film cooling holes that extend through an exterior surface of said airfoils, the plurality of film cooling holes including at least a first subset of film cooling holes, wherein said first subset of film cooling holes break through said exterior surface at geometric coordinates in accordance with Cartesian coordinate values of X, Y and Z as set forth in Table 1, wherein each of said geometric coordinates is measured from a reference point on a leading edge rail of a platform of the vane.
 2. The vane as recited in claim 1, wherein said Cartesian coordinate values of Table 1 are expressed in inches.
 3. The vane as recited in claim 1, wherein said reference point includes a pin hole of said platform.
 4. The vane as recited in claim 1, wherein said plurality of film cooling holes are spaced along a span of said airfoil body in multiple collinearly aligned rows.
 5. The vane as recited in claim 1, wherein said first subset of film cooling holes are disposed on a pressure side filet of said airfoil body.
 6. The vane as recited in claim 5, further comprising at least a second subset of film cooling holes disposed on a pressure side, a suction side and a leading edge of said airfoil body.
 7. The vane as recited in claim 1, wherein the airfoils extend between inner and outer platforms, the inner and outer platforms include a second plurality of film cooling holes that extend through an exterior surface of said platforms.
 8. The vane as recited in claim 1, wherein the plurality of film cooling holes included in the first subset of film cooling holes are the only cooling holes disposed within a radially outward fileted region of a pressure side of each airfoil.
 9. The vane as recited in claim 1, wherein the vane is a first turbine stage vane.
 10. A method for cooling a vane doublet, comprising: generating a film cooling layer across a pressure side filet of each airfoil in the vane doublet by passing air through a plurality of film cooling holes that extend through an exterior surface of said airfoils, the plurality of film cooling holes including at least a first subset of film cooling holes, wherein said first subset of film cooling holes break through said exterior surface at geometric coordinates in accordance with Cartesian coordinate values of X, Y and Z as set forth in Table 1, wherein each of said geometric coordinates is measured from a reference point on a leading edge rail of a platform of the vane.
 11. The method of claim 10, further comprising generating a film cooling layer across at least one of a pressure side, a suction side and a leading edge of said airfoil body by passing air through a plurality of film cooling holes disposed across the at least one of the pressure side, the suction side and the leading edge. 